diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index f473ddf..5c48612 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -779,6 +779,11 @@
 		ix = curp->p_idx;
 	}
 
+	if (unlikely(ix > EXT_MAX_INDEX(curp->p_hdr))) {
+		EXT4_ERROR_INODE(inode, "ix > EXT_MAX_INDEX!");
+		return -EIO;
+	}
+
 	ix->ei_block = cpu_to_le32(logical);
 	ext4_idx_store_pblock(ix, ptr);
 	le16_add_cpu(&curp->p_hdr->eh_entries, 1);